This circuit is for traditional old-style telephone lines found in an American 1980s documentation. Components are common and the optical coupler can be replaced with an equivalent.
This ultra-low noise amplifier and simple power supply was found in Analog Devices documentation from the...
This circuit was found in a 1970s documentation. The integrated circuit used is uncommon today....
This control was obtained in an old publication from 1985 and uses a triac, which today can be of...